Would be nice to see an OC game.
A couple of thoughts. I think if the system is meaty, potential new folks lose some interest in a supers game (if an OC Champions game opened, I'd have no interest). Inversely, I think while stateless works/hadsworked, there are quite a few folks that want some dice, but more action (fast combat) oriented not loaded down in powers/feats/abilities. KISS - a system folks can grab easily without needing 3+ books to understand the mechanics is good. Simpler the better, which makes it hard with powers I know.
As for Sky High/Academy, this is what we did three'ish years ago with Coral Springs. But to be different it was in the water, not floating in the sky. It had a good run. That said, I think the city idea would be good. It could have some meta/mutie/Sky high but not be limited.
While you have a lot of lore ready to go, I'd ponder lessening it to simply the essential stuff. Let players build into the lore. You don't need a Legion of Doom (Villain group), but what's wrong with a player apping into the Academy side trying to do good despite Legion of Evil Parents being at their back. I'm thinking, and could be me, but in an OC game, players like to contribute that sort of stuff, its their char BG/development, but contributes to a growing OC world. Secondary to that, its good you have a solid basis of world but check for potential collaborators too, a few other sounding voices at least could help contribute to a theme more inclusive.
From Coral Springs, I can say there are plenty of imaginative players ready to play OCs, given the right tools to create what they want, just be ready to stick to guns on the weird/banned concepts (like if you don't want time manipulation or completely invulnerable).